Netplan (currently) does not support MACVLAN interfaces. So here I use a post-up hook script to create a MACVLAN interface for the host in order to communicate with containers.

• Netplan config.

  # cat /etc/netplan/netplan.yaml
  network:
    version: 2
    ethernets:
      enp1s0:
        dhcp4: false
        dhcp6: false
        accept-ra: false
      lan:
        dhcp4: false
        dhcp6: false
        addresses: [192.0.2.0/24]
        gateway4: 192.0.2.1
        nameservers:
          search: [lan]
          addresses: [192.0.2.53]
    vlans:
      untrust:
        id: 510
        link: enp1s0
        dhcp4: false
        dhcp6: false
        accept-ra: false

• Networkd post-up hook scripts.

  # cat /etc/networkd-dispatcher/degraded.d/10-macvlan-enp1s0
  #!/bin/bash
  
  MYNIC="enp1s0"
  
  if [[ "${IFACE}" == "${MYNIC}" ]]; then
    ip link add lan link "${IFACE}" type macvlan mode bridge
  fi

• Enable networkd-dispatcher.

  systemctl enable --now networkd-dispatcher.service

• LXD starts containers using a MACVLAN interface.

  # lxc profile show default
  config: {}
  description: Default LXD profile
  devices:
    eth0:
      name: eth0
      nictype: macvlan
      parent: enp1s0
      type: nic
    root:
      path: /
      pool: SSD
      type: disk
  name: default
  used_by:
  
  # lxc profile show untrust_vlan
  config: {}
  description: ""
  devices:
    eth0:
      nictype: macvlan
      parent: untrust
      type: nic
  name: untrust_vlan
  used_by:

• Apply config.

  netplan apply